Compressor piston ring



Aug. 17, 1948. A. KALITINSKY 2,447,125.

COIPRESSDR PISTO RING Filed Jan. 30, 1945 2 Shoots-Shoot 2 62 6B, 64 es3g a2 16 y gn FIG.2.

INVENTOR Patented Aug. 17, 1948 UNlTED STATES PATENT OFFICE COMPRESSORPISTON RING Andrew Kalitinsky, Eaglevllle, Conn., assignor to UnitedAircraft Corporation, East Hartford, Conn., a corporation of DelawareApplication January 80, 1945, Serial No. 575,339

1 14 Claims. This invention relates to a compressor piston constructionparticularly adapted for use in a free-piston unit.

When an engine and compressor unit is used in pumping media of difierentdensities the change in density may be compensated for by providingports in the wall of the compressor. The ports are opened or closed foradjusting the effective volume of the compressor as described in thecopending Kalitinsky application, Serial No. 550,884, filed August 23,1944, now Patent No. 2,441,272, May 11, 1948. For effective sealing, thepiston rings on the compressor piston must be more widely spaced thanthe axial dimension of each port and the thickness of the piston must beenough greater than this dimension to receive and support the rings. Afeature of this invention is a piston having a single piston ring on itsperiphery, the width of which is greater than the axial dimension of theports. Another feature is the formation of integral ribs on theperiphery of the ring the spacing of the ribs being greater than theaxial dimension of the port.

In free-piston units the mass of the reciprocating piston assemblycontrols the frequency so that for high frequency operation a low pistonmass is necessary. A feature of this invention is a piston ringconstruction for the compressor piston which will be substantially aswide as the piston and will permit the use of a relatively thin lightweight piston. Another feature is the arrangement of the ring tominimize leakage past it.

Other objects and advantages will be apparent from the specification andclaims, and from the accompanying drawings which illustrate anembodiment of the invention.

Fig. 1 is a sectional view through a free-piston unit.

Fig. 2 is a fragmentary sectional view on a larger scale of the ring forthe compressor piston- Fig. 3 is a fragmentary view of the periphery ofthe ring.

The unit in which the piston construction is shown includes an enginecylinder l having reciprocating pistons [12 and it to which thecompressor pistons i6 and IS in cylinders and 22 are integrallyconnected. Sleeves 24 and 25 attached to the compressor pistons completethe reciprocating piston assemblies. The sleeves in combination withstationary pistons 28 and 3! form air spring cylinders. I

The piston assemblies are moved apart by the burning of fuel injectedinto the engine cylinder through one or more nozzles 32. Air compressedin the air spring cylinders on the power stroke returns the pistonassemblies. The assemblies are always maintained at equal distances fromthe center of the engine cylinder by a linkage, not shown.

Intake manifold 42 which extends around the compressor and enginecylinders conducts air to intake valves 44' in the heads of thecompressor cylinders through which air alternately enters opposite endsof the cylinders. The compressed air leaves the cylinders throughdischarge valves 46 also at opposite ends of the compressor cylindersand passes into a central scavenge duct 48 and end chambers 58 and 52.,These chambers may be interconnected by a scavenge manifold, not shown.1 a

Compressed gas from the scavenge chambers enters engine ports 54 and 5Bwhich are uncovered by pistons l2 and it at the end of the power stroke,thereby permitting air to be blown through the engine cylinder. Gas inthe engine cylinders is discharged through exhaust ports 58 into exhaustmanifold 60.

Each compressor cylinder may have a number. of axially spaced rows ofspill ports 62 to permit discharge of air without compression from thecylinder. Each row of ports may be individually controlled by a band 64,Fig. 2, extending around the cylinder between projecting ribs 66extending from the cylinder. Each band has a number of openings 68corresponding in spaclngto the ports so that by angular motion of theband the openings 6-8 may be aligned with the ports 62. This arrangementis described in detail in the copending Kalitinsky application, abovereferred to.

As shown in Fig. 2, the compressor piston i8 has a tongue 10 on itsperiphery engaging in groove 12 in a wide piston ring 14 which extendsaround the cylinder and is split so that it expands by its resiliencyinto engagement with the wall of cylinder 22. The outer side surfaces 16and I8 of the piston ring are beveled to conform to the taper of thecompressor piston and to form continuations of the side walls of thepiston.

On the periphery of the piston ring may be formed integral ribs and 82which are at the outer edges of the ring and which, as shown, are spacedapart a distance greater than the axial As shown in Fig. 3, the split 84in the piston ring is substantially Z-shaped, with the parallel barelements of the Z spaced apart a distance greater than the thickness oftongue It. By this 3 arrangement leakage of air past the split in thepiston ring is reduced to a minimum.

It is to be understood that the invention is not limited to the specificembodiment herein illustrated and described. but may be used in otherways without departure from its spirit as defined by the followingclaims.

I claim:

1. A compressor cylinder having a number of ports in its outer wall, anda piston in said cylinder, in combination with a single piston ring onthe periphery of the piston and engaging with the cylinder wall, saidring having an effective width greater than the diameter of the ports.

2. A compressor cylinderhaving a number of ports in its outer wall, anda piston in said cylinder, in combination with a single piston ring onthe periphery of the piston, said ring having integral cylinder engagingribs on its periphery.

3. A compressor cylinder having a number of ports in its outer wall, anda piston in said cylinder, in combination with a single piston ring onthe periphery of the piston, said ring having integral cylinder engagingribs on its periphery, the spacing of which is greater than the axialdimension of the ports.

4. A compressor cylinder having a number of ports in its outer wall. anda piston in said cylinder, in combination with a single piston ring onthe periphery of the piston and engaging with the cylinder wall, thering being substantially as wide as the thickness of the piston and atleast as wide as the axial dimension of the ports in the cylinder wall.

5. A compressor cylinder having a number of ports in its outer wall, anda piston in said cylinder in combination with a single piston ring onthe periphery of the piston, the ring being substantially as wide as thethickness of the piston, and having integral ribs on its outer peripheryclosely adjacent to the side surfaces of the ring.

6. A ring for a compressor piston having a width substantially equal tothat of the piston, and having ribs on its periphery, said ring beingsplit and having means on its inner surface for engagement with thepiston to retain the ring in place on the piston.

7. A ring for a compressor piston having a width substantially equal tothat of the piston, and having ribs on its periphery, said ring beingsplit and having a groove on its inner surface by which it is located onthe periphery of the piston.

8. A ring for a compressor piston having a width, substantially equal tothat of the piston, and having ribs on its periphery, said ring beingsplit to permit expansion, the split being 2- shaped.

9. A piston having its outer surfaces tapering toward the periphery, incombination with a split piston ring on the periphery, the side surfacesof the ring tapering and forming continuations of the piston surfaces.

10. A piston having its outer surfaces tapering 4 toward the periphery,in combination with a split piston ring on the periphery, the sidesurfaces of the ring forming continuations of the piston surfaces, saidring having integral ribs on the periphery.

11. A piston having its outer surfaces tapering toward the periphery, incombination with a split piston ring on the periphery, the side surfacesof the ring forming continuations of the piston surfaces, said ringhaving' integral ribs on the periphery, the split in the ring beingZ-shaped to minimize leakage.

12. A piston having a ring engaging means on its periphery, and a pistonring substantially equal in width with the thickness of the piston andhaving means on its inner periphery cooperating with the ring engagingmeans, said ring having integral ribs on its outer periphery forengagement with a cylinder wall.

13. A piston having a rib on its periphery, and a piston ringsubstantially equal in width to the thickness of the piston, and havinga groove in its inner periphery cooperating with the rib on the piston,said ring being split and having integral ribs on its outer peripheryadjacent to the side surfaces of the ring for engagement with thecylinder wall.

14. A piston having a rib on its periphery, and a piston ringsubstantially equal in width to'the thickness of the piston, and havinga groove in its inner periphery cooperating with the rib on the piston,said ring being split and having integral ribs on its outer peripheryadjacent to the side surfaces of the ring for engagement with thecylinder wall, the split in the ring being Z-shaped with the barelements of the Z being parallel to and spaced from the side walls ofthe groove.

ANDREW KALITINSKY.

REFERENCES crrEn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 316,749 Crouan Apr. 28, 1885676,523 Wood June 18, 1901 1,020,819 Hanson" Mar. 19, 1912 1,040,472Wade Oct. 8, 1912 1,048,918 Van Vleck Dec. 31, 1912 1,216,218 Eddowes sFeb. 13, 1917 1,259,391 Glidersleeve Mar. 12, 1918 1,295,329 KennedyFeb. 25, 1919 1,386,707 liartog Aug, 9, 1921 1,437,869 Sullivan Dec, 5,1922 1,618,345 Kuyken Feb. 22, 1927 FOREIGN PATENTS Number Country Date2,571 England 1857

